An ejector refrigeration cycle is known as a vapor compression refrigeration cycle device that has an ejector serving as a refrigerant decompressor.
An ejector disposed in such an ejector refrigeration cycle has a nozzle that defines a refrigerant passage (i.e., a nozzle passage) therein, a refrigerant suction port, and a pressure increasing part (i.e., a diffuser passage). An injection refrigerant is injected from the refrigerant passage at a high speed. The refrigerant suction port draws refrigerant, which flows from an evaporator, using suction power of the injection refrigerant as a suction refrigerant. The diffuser passage increases a pressure of mixed refrigerant of the injection refrigerant and the suction refrigerant. The refrigerant of which pressure is increased in the diffuser passage flows to a suction side of a compressor.
As a result, a pressure of the refrigerant drawn into the compressor can be high according to the ejector refrigeration cycle, as compared to a normal refrigeration cycle in which an evaporating pressure of refrigerant in the evaporator is substantially equal to a pressure of the refrigerant drawn into the compressor. Therefore, according to the ejector refrigeration cycle, consumption power of the compressor can be reduced, thereby improving a coefficient of performance (COP) of the ejector refrigeration cycle, as compared to the normal refrigeration cycle.
Patent Literature 1 discloses an ejector that further has a swirl causing part (i.e., a swirl space) causing refrigerant to swirl before flowing into the nozzle passage. The ejector disclosed in Patent Literature 1 causes a subcooled liquid-phase refrigerant to swirl in the swirl space such that refrigerant swirling about a swirl center is decompression boiled, thereby biphasic refrigerant flows into the nozzle passage. The biphasic refrigerant in this case means a refrigerant having gas-phase refrigerant swirling on an outer side in the swirl space and liquid-phase refrigerant being concentrated on an inner side and swirling about the swirl center.
It is an objective of the ejector disclosed in Patent Literature 1 to facilitate a boiling of the refrigerant in the nozzle passage, and thereby to improve energy conversion efficiency in a conversion of pressure energy of the refrigerant to kinetic energy in the nozzle passage. In addition, it is another objective of the ejector to increase a pressure increase degree of the refrigerant in the diffuser passage by improving the energy conversion efficiency, and thereby to further improve the COP of the ejector refrigeration cycle.